What was found in Chelmsford's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 1600 µg/L 16% of the EPA limit 10000 µg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2019 | 3/3 | SYR4 |
| Fluoride | 500 µg/L 13% of the EPA limit 4000 µg/L Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2018 | 1/3 | SYR4 |
| Chlorite | 445 µg/L 45% of the EPA limit 1000 µg/L Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2019 | 1/3 | SYR4 |
| Copper | 161.5 µg/L 12% of the EPA limit 1300 µg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2019 | 2/3 | SYR4 |
| TTHM | 79.81 µg/L 100% of the EPA limit 80 µg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2019 | 3/3 | SYR4 |
| Gross Beta Particle Activity | 45 pCi/L No EPA limit set Highest in the city: EAST CHELMSFORD WATER DISTRICT · 2,800 people · 2017 | 1/3 | SYR4 |
| Chloroform | 44.95 µg/L No EPA limit set Highest in the city: EAST CHELMSFORD WATER DISTRICT · 2,800 people · 2019 | 2/3 | SYR4 |
| Barium | 43.6 µg/L 2.2% of the EPA limit 2000 µg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2018 | 3/3 | SYR4 |
| Lithium | 30.8 µg/L No EPA limit set Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2024 | 1/3 | UCMR-5 |
| Total Haloacetic Acids (HAA5) | 23.19 µg/L 39% of the EPA limit 60 µg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2019
Highest in the city: 26.3 µg/L — EAST CHELMSFORD WATER DISTRICT · 2,800 people · 2019 | 3/3 | SYR4 |
| Bromodichloromethane | 21.825 µg/L No EPA limit set Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2019 | 2/3 | SYR4 |
| Dibromochloromethane | 21.34 µg/L No EPA limit set Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2019 | 2/3 | SYR4 |
| Combined Uranium | 17.355 µg/L 58% of the EPA limit 30 µg/L Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2019 | 1/3 | SYR4 |
| Trichloroacetic Acid | 15.1 µg/L No EPA limit set Highest in the city: EAST CHELMSFORD WATER DISTRICT · 2,800 people · 2019 | 2/3 | SYR4 |
| Bromoform | 13.568 µg/L No EPA limit set Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2019 | 2/3 | SYR4 |
| Dichloroacetic Acid | 11.3 µg/L No EPA limit set Highest in the city: EAST CHELMSFORD WATER DISTRICT · 2,800 people · 2019 | 2/3 | SYR4 |
| Monochloroacetic Acid | 7.02 µg/L No EPA limit set Highest in the city: EAST CHELMSFORD WATER DISTRICT · 2,800 people · 2019 | 2/3 | SYR4 |
| Arsenic | 4.6 µg/L 46% of the EPA limit 10 µg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2018 | 3/3 | SYR4 |
| Dibromoacetic Acid | 4.545 µg/L No EPA limit set Highest in the city: EAST CHELMSFORD WATER DISTRICT · 2,800 people · 2019 | 2/3 | SYR4 |
| Monobromoacetic Acid | 2.647 µg/L No EPA limit set Highest in the city: NORTH CHELMSFORD WATER DIST · 7,660 people · 2019 | 2/3 | SYR4 |
| Dichloromethane | 2.21 µg/L 44% of the EPA limit 5 µg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2019 | 2/3 | SYR4 |
| PFOA | 0.0089 µg/L No EPA limit set Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2024 | 1/3 | UCMR-5 |
| PFOS | 0.0072 µg/L No EPA limit set Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2024 | 1/3 | UCMR-5 |
| PFBS | 0.0042 µg/L No EPA limit set Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2024 | 1/3 | UCMR-5 |
| Pfpea | 0.0037 µg/L No EPA limit set Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2024 | 1/3 | UCMR-5 |
| Lead | 0.0024 mg/L 16% of the EPA limit 0.0150 mg/L Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2025
Highest in the city: 0.0035 mg/L — NORTH CHELMSFORD WATER DIST · 7,660 people · 2025 | 3/3 | LCR |
| Pfhxa | 0.0035 µg/L No EPA limit set Main supplier: CHELMSFORD WATER DISTRICT · 28,750 people · 2024 | 1/3 | UCMR-5 |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Chelmsford
| Supplier | Population served |
|---|---|
| CHELMSFORD WATER DISTRICT | 28,750 |
| NORTH CHELMSFORD WATER DIST | 7,660 |
| EAST CHELMSFORD WATER DISTRICT | 2,800 |
Frequently asked questions about Chelmsford tap water
Is Chelmsford tap water safe to drink?
EPA testing detected 27 contaminants in the water serving Chelmsford. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Chelmsford?
3 public water suppliers report drinking-water monitoring for Chelmsford, Massachusetts to the EPA. Each is listed above with its population served.
What contaminants are in Chelmsford's water?
The contaminants EPA monitoring detected in Chelmsford include Nitrate, Fluoride, Chlorite, Copper, TTHM. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.